Delamination induced by non-synergistic strain hinders crack extension in TC4-2024 Al laminated composites

In laminated composites, delamination is usually considered a failure mode and its strengthening effect is ignored. In this study, TC4-2024 Al laminated composites with different foil thicknesses were prepared by spark plasma sintering. The increase in layer thickness exacerbates the non-synergistic strain between layers and induces delamination. It was found that the delamination isolated the local stress transfer during the tensile process and cut off the crack extension path, thus effectively hindering the crack extension. To analyze the mechanism of delamination, phase-field simulations were innovatively conducted based on the Al–Al3Ti coherent interface and TC4-Al3Ti semi-coherent interfaces. This confirmed that dislocations at the semi-coherent interfaces act as crack sources and accelerate delamination. This work reveals the connection between delamination, non-synergistic strain, interface structure, and crack extension, which provides ideas for optimizing the structure of laminated composites.